Distance finding system



F. EICKE DISTANCE FINDING SYSTEM I A il 30, 1935.

Fi led Dec. 26, 1951 2 Sheets-SheeLZ l V I 1. 5. Y- i q k INVENTOR. ERMA/0N0 BCKE A TORNEYS.

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Patented Apr. 30, 1 935 This .invention'relates to improvements in apparatus employedin the art of navigation and has aireference to a method and means of determining distances betweentwo points, at least one, of which 5 vis moving relative to the other. V

The invention, which is particularly useiulon shipsinavigating at sea, makes useof signals; such as radio signals, transmitted from a distant sending point, such as a land station'or ship, to deter-- mine the distance thereotfrom the point of =receptionbf the signals. As 'dis'tinguishedirom known systems, wherein it is necessaryin every t. 'instancetc establish communication between 'ai ship 'and 'a land station inorder to procure "data, for the purposeof ascertaining thepcsition of the 1 I ship, it is possible, withthepresent system,- to quickly calculate the'iapproximate distance-betweena :shipand a land station; or between'two ships, without resorting to interchange" of comx' munications; and to: more :accurately determine such" distance-between ships by'obtaining infor,- mationirom the distantfship as toits courseand --speed"of-travel. In either event, the present systm makes possible, through the employment of a direction finder such as a rotatable antenna and an indicating mechanism controlled thereby, the ascertainment of a "certain factor or factors by means of which the--='distance "between two points maybe approximated in a simple 'andrapid mannenby triangulation.-

a The inventive idea involved is capable'of. receiving a variety of expressions, one of which, for purposes of illustration; is shown in the accompanying drawings, wherein:

Figure 1 is a perspective view, partially in diagram, of an apparatus and. circuits employed in CODI'IGCtiO IIWJ ih the ,inventi'onyand .1 1 FiguresZ to '4 are diagrammatic views illustratingthe method of ca -gulation. i

:rThe apparatus; awhich is especially useful in foggy weatheruand b'yvmeans of; which certain factors are determined inorder to icalculatethe distance between diiieren't points,wi1l*first be described. In its preferred form, the apparatus is constructed to receive radio signals, such as those which, are .now commonly: used. for-1, identifying landstations and ships. .To this end, there is provided a, 'directionefindinglmechanism in-' the formof loop antenna 5fmounted upon a rotatable shaft 6 which issupported-upon a suitable base "I.

Said antennais to becoupled-with'a radio receiving circuit 5,, of anynknown design by means of which the received signals will be' made audible andwhen the antennarisrotated, as foriinstance lculating aposition by trian- V t 1,999,232 g nIs'rANoE-rmnnic srs'rsivi- 7' "Ferdinand Eicka Bronx, N;v Yr, assignor to Ship OFFICE" A 'ra' tion of New'Yolfk v Applicaticn'December 26, 1931, Serial No. 583,270

r the transmitting source A control the operation of as the calibrated meters mounted upon the base 1 terminal to the movable on the units from 1 to 10.

i-acrossa circuit which ductor 16, the movable "parallel relationto and joined to the conductor right. angles to the, bar

:by the handle 8 the intensity of a receivedsignal will vary until theantenna is in-a position wherein its plane isatrightangles tothe direction of of said signal, at which time the signal will no. longer be heard and the 5 direction. ofsaid source is thereupon determined: The upper end of the shaft 6 carriesan instru 11181113, conventionallyshown at; 9, utilized tosight "visibleobjects for a purpose which will aappear in the course oflthe description. 4110 The rotation ofthe antenna islemployedqto indicating devices; such 1 l} and I I; by means of which certain factors, .us edinicalculating distances in the manner later/to appear; alre defi-r i5 1 'nitely ascertained, 'Inorder to accomplish the control of the meter i0, an electric circuit ie-pros *vid'ed 'in which is included 'a fixediresistance-iz' I tact arm-l3 carried bythe shaft 5. One end (Iiisaid resistance is connected too'ne pole of bat iteryi through the'conductor l4,.while the other pole of said battery is .said resistancelby the conductorl; 'Themet'er I [lie bridged across this circuit by connectingone terminal thereof direct to battery and the other joined to thei'centeriof contact arm 13 "so that,

when the latter is at right angles totheresistance 12, which isyin turn, at a similar angle to the lubbe'r-lineof the ship, the resistance in 3 themeter circuit is at minimum'and the indicat'or of said meter stands' at '0. However, a vmovement-of the arm 13 to eitherrside of .the

" point-of connectionof the conductor I 5 with the resistance l2 will includea'part of the latter in 3 the meter circuit and cause said indicator to .move over, thefdial of the meterwhich has there- The second meter 1 l, the dial of which is 02.11- brated, for example, with the numerals 10.to 20, 1'

each' representing a unit which enters into the calculations to be later' described, is bridged includes battery, "conresistance. I! carried? by vtheshaft'fi, and fromthence'throughthe con-. :4 x ductor 58 back to battery. Said resistance is engaged with and movable overthe stationary contact bar I9. supported'upon the baset'l .in

directly overithe resistance l2,and is connected to one lterminal'oi'the 9 ,met'erxl i, the, other terminal of which .being' l6, thus completing the bridge for the meter. With the resistance Hat IS, the indicator of. the

"meter pfl will point to the 10 and, aszsaid resistance is moved over the bar in either direction, said indicator will respond to the variations in the resistance in the meter circuit to indicate units on the meter dial from 10 to 20.

Referring now to Figures 2 and 3, it is first pointed out that, with two ships, both of which are under way, it is possible, with the present system, to make two different calculations as to the-distance between said ships, one of which calculations will be more accurate than the other. In other words, it may not be necessary, after the direction of a distant ship is ascertained, to obtain more than a :rou'ghfestima'te as to its position, but, on the other hand, if the direction of the distantship is'su'chthat the courses of the vessels may intersect, it would then be desirable to ascertain a closer approximation of the distance therebetween. In making the less accurate calculation, only the meter it need be employed to determine one of the required factors for the mathematical equations.

(later to appear) by which the unknown dista'hce is obtained, while both meters are used 1 when securing a more accurate determination of said distance.

Figure 2 illustrates diagranimaticallythe man ner in which, by triangulation, the'less accurate calculation is made and it is in thisin'stance, as

previously mentioned, that it is entirely unnecese sary for the two ships to communicate with each The approximate calculation, presently "to be described-in.:c'onnection withFigure 2, is

"the "beam distance between the two ships, that is, the distance between two imaginary lines irepe resenting .the "courses of the ships, assuming, for the moment, that they are running parallel to -.each oth'er. ,Th'u's,.-as viewed in Figure 2, the'line 'ofsth e right angle triangle, 'upon which all beam. calculations are based "and the length of which is the unknown factor tobe determined. represents the-beam distance between the two a ships whichyfor purposes of this calculation,

areltheoretically traveling on parallel. courses.

tance between the axis of theshaft Bsand the point of contact of the 'arm' 13 with the resist- 'ance i2 when the two" are at right angles to one another. This known cohst'aiitiactor is represented by a definite-number of units, for example 10 and the "meter is so calibrated and affected by the resistance I2 that the amount of deviation of the arm l3 relative to its'right Zat'definite periods of time and the "desired factor .issthe niiierence between said readings.

angular position is indicated on said meter in units corresponding to those into which'the'line a is divided. This amount of deviation is utilizedto determine the second factor of the equa- 1 tion which is represented by theline 'b.

in so doing,"two readings of the meter i ii must be taken Jt'nird factor, representedbytheline C, is the combined-speeds 'of the two vessels in approach- :ing a point where their "courses might inter j sect. The s'p'e'ed of the distant ship is; of course, :unknown in the present example, but, for pur- 1 poses of this calculation, the speed of each ves- 1 "sel' is taken as approximately.fiiteenjknots.' Such assumption is, as a matter of tact, common nautical practice when the actual speed of a ship has not been determined and is sufficient for purposes of approximate calculations. Therefore, with a combined speed of thirty knots per hour, the speed traveled by the two vessels during the above mentioned interval of time can be easily calculated, the result being the third factor required for the mathematical equation by which the beam distance? between the two ships is determined.

A specific example of the method by which the 'beam distance? between two ships may be as-' certain'ed will now be described. It will be assumed, as shown in Figure 2, that the navigator on the ship 20 has picked up the radio signal broadcast by the distant ship 25 by means of the antenna'5, which is then rotated until the deadpoint'is reached in which the radio receiving set 5} coupled to said antenna no longer responds to said signal. The position of the antenna relative to its axisof rotation is then such as to indicate the direction of the source of the transmitted signal If. it should so happen that the direction is dead ahead, the ship is immediately stopped, or

its course changed, until the dead-point of the antenna .can be picked up 'ofi the port of star board bow of the vessel. When such a relative po- :sition is determined, such as indicatedby the line 22, wherein the directionis shown as offithe starboard bow of the ship, thenavigator immediately .records the exact time and the reading onthe meter it], which latterwill be assumed 'tobe 6, the indicator 'of said meter having respon'dedto the movement of the armlfl3 over the resistance i2.. At the expiration of one minute, or any otherdefinite intervalof-tima the antenna 5 is turned again 'until the dead-pointis reached; whereupon a-second reading takenifromv the meter l will be recorded, which, f-orexample, :will be 5, it being understood that the relative positions of the two ships has changed duringsaidinterval of time. The; difierence between ,the two "readings-,-'which is l-,.now determines the second factor representing the line hit being recalled that the first factor is the constant I 0 for the linea; lIhe' third factor 0 is. the ,combined estimated distancetraveled by the two ships inrthe one-minute intervalbetween the two readings of the meter ll), said distance being .5 knot; 1The mathematical equation for determining the distance r may now be represented by V b zzanc the two ships is five nautical miles. The' navi- 'gator'being' thus informed-and knowing, by the positions of the antenna at the time of the. two

readings were taken that the courses of the two" ships were likelyto intersect, proceeds accord- ".ingly by changing the course of his vessel toavoid the z'p'ossibility'of collision.

(ill

b'ecalculated, communicate with the latter ship to ascertain its speed and course. Upon being informed that the speed of ship 2t is, for instance,

. twenty-live knots and that its course is diagonal relative toship' '20, the navigator immediately takes the-first reading on the meter 1 I q and after the lapse of a definite periodof time, such as one 1 minute, takes'the second'reading, on said meter in the same manner as previously described; It

' I. bl. Bearing. intmindmthat the factoral is not flcons'tant inthe example now being explained, as

V wasthe factor 'a inthe -beatn'calculation, it is.

:LlO

' the meter] I; which reading is taken concurrently withfthe second reading vonsth'e meter H3. The;

J factor alis variablel'due to the fact thattheresistance I! is movable over the fixed contact bar .l l9 and,,consequently, the actual distance between necessary to. obtain said factor bya reading on the shaft 6 and the point of contactof the ref "sistance on said barvarieswith theposition of said resistanceraslthe shaft 6 is rotated.- Thus;

I assuming that the line 22w represents the directionxoff the distant .shipaatthe time-ofthe first readingand that-the direction at the time of the second. reading cwas along theline. a If; it: will be I apparent that theiactual length of :thelatterl line is greater. than that of the line a which was used as constant factor in'the firstfexample. The" meter II is so calibrated and controlled, by the resistance I? that it will indicate'the length of the line a! at the timeof taking thereading'and it will be'assumed that the indicator of-the meter is pointing to 12. Therefore, it is now known that .the first factor is 12 and that the second factor,

represented by the line bi, is-2. Having been. in-

formed that the distant ship 2! is making twentyfive knots and knowingthe speed of'the ship 20,

Consequently, the distance represent d by ,the line :1: of Figure 3 is approximated at 4.5 nautical miles. y

Should it become desirable or necessary to es- V tablish the distance of the ship relative to a fixed point, such as ashore station 23 (Figure 4) from which a radio signal is being broadcast, substantially the same procedure is followed as in the first example. An initial direction 24 is first determined by the antenna 5 and ,a reading 'or the meter l0 taken; Then, after a lapse of. 2. definite period of time, a'swhen the ship has reached the position at the left of said figura'a. second reading is taken on, said meter.

Knowing the constant factor of 10 corresponding to the factor a of the first example, also the factor represented by the difference inthe two; readings which, for" purposesof illustration is assumed to be 1, and

further knowing the distancethe ship has traveled between the times of taking the two readings,.the distance from the shipto the shorestag tion may be ascertained. Assuming that the ine terval of time was one-half hour andthat the speed of the ship was twenty knots, the equation reads 7 ;10:1:::n:10

thus showing that theship'is one hundred nautical miles from; the station 23 at the time of the second reading. It is obvious from the foregoing that the same calculationmay be r'nade' by; taking 'two readings, without' the lapse Ofiifl definite .periodof time, from twodifferent shore stations, V the distanceJbetwee'riwhich isiknownto the will be assumedagain that the difference between. V

thetwo readings is 2, lthus determining the factor navigator-on the ship..-*. 1

w When a distant object,such as a point on "shore, or another ship,. is visiblelto the navigator, the

same calculationsas-heretofore described may be effected by the-use;of.the sighting instrument 9 mounted upon the shaft 6; .By. training said 'in-' struinent upon the distant object, the 'shaftds-rotated to cause the meters l0 and l I to indicate the units on the scales thereofeby. which thefactors 41 L1) and "bl are obtained and, then; with theother :known factor, namely, .thespeed of the 'ship, .the. distancebetween the latter and" the distant point may. be ascertained.

' What is claimedisz a 1. In a system; 'of the class described, a movable direction-finding device, .a rotatable shaft there- I for, means to turn said shaft and device; a radial arm attachedlto said shaft andencircled'bya resistance winding, .a" horizontal. conductor bar contacting with s'aid' resistance. winding and spacedsufliciently from saidshaft so that the upon movement of said direction-findingdevice,

an electrical circuit connected to 'said'arm and bar, and a meter in said electrical circuit and operatedl to indicate a reading by a movement of said direction-finding device and consequent rotation of said shaft. 2. In a'system of the-class described, a movable direction-finding device, a. rotatable shaft therefor, means to turn said shaft and device, a radial arm attached to said shaft and encircled by a resistance winding, a horizontal conductor bar contacting with said resistance winding and spaced sufficiently from said' shaft so that the distance of its contact from said shaft will vary upon movement of said direction-finding device, another radial arm projecting from said shaft in spaced relation to the first-named radial arm and parallel thereto, another horizontal bar spaced'from and parallel to the first-mentioned 25 distance of its contact from said shaft will vary bar, said other horizontal bar beingprovided with a resistance winding contacted by the second-named radial arm at a plurality of points depending'upon therotation of said shaft, electrical circuits one of whichincludes the firstmentioned arm and barand the other the secend-mentioned arm andbar, and a meter in each of said circuits operated by movements of said direction-finding device; 4

3. In a system of the class described for a vessel, a movable direction-finding device;. a shaft connected to said devicei resistance elements normally at right angles to each other; a plurality of radial arms extending radially from said shaft individual. to each of said resistances, and arranged to vary said resistances individually; circuit connections including said resistances; and

7 indicating devices connected in each of said circuit connections for indicating the angular position of the associated arms, said radial arm resistances and circuit connections being such that the two indications provide a basisfor determining thecourse of the vessel; s

4;. In a' system of the class described; a movable direction-findingdevice; a shaft connected to said device and rotated thereby; a plurality of Vidu'al to and engaged by' the other of said arms;

, said 'second'arms carrying a resistance engaged shaft therefor; means for turning 'saiddevice and' shaft; a resistance element; an indicator; a source of energy; an electrical circuit including :saidres'i'stance; indicator and source of energy;

means controlled by the rotation of saicl shaft for varying the amount of resistance in said circuit wherebythe angular position of :said shaft is indicated; a second resistance element normally at right angles to said first resistance; a second indicator; a' second source of energy; a'second .-e lectri'cal circuit including "said resistance, indicatoran'd source'of. energy; and means whereby a variable amount o'fs'aid second resistor is con nected in said second circuit in accordance with the :angular rotation of said shaft, said first and second-indications providing indications for determining thecourse and position of the vessel. 6. In a systemof the class described; a movable directional antennafor vessels; a shaft connected thereto and rotatable therewith; a' first arm and a second arm connected to saidantenna. and

rotatable therewith; circuit connections to each of said arms includingia resistance and indicator means whereby ,as said shaft is rotated, one of said resistances is decreased in value while the other is increased and vice versa for; variably operating said indicators, said indicators providing'indicati'on'whichjointly indicates the course and position of the vessel.

. ;'7.'In a system of the class described; amovable idirectional indicator; a shaft connected thereto and rotatable therewith; apair of radial resistance arms extending from said shaft; and a means wherebyLasrthe shaft rotates, the resistance value. of one of said resistances is increased and the resistance value of the other of said FERDINAND 

